If you have an application that requires a durable vibration, or a high confidence MTTF rating, consider our Linear Resonant Actuator vibration motors as an alternative to long life brushless vibration motors. But, understand that that longer life and control does come at a slightly increased cost of complexity - continue reading to find out more.

General Construction for a Y-axis LRA Linear Vibrator

Precision Microdrives Y-axis LRA Linear Vibrator Motor

The illustration above shows the general arrangement of parts within a Y-axis LRA vibration motor. Those readers familiar with audio engineering will note that the voice coil drive is very similar to that loud speaker. However, instead of a cone that generates sound pressure waves, there is a mass that generates vibrations.

Below is another LRA which works in the same way, however the vibrations are directed in only the Z-axis. This offers users a greater choice in design as they can produce vibrations in either horizontal or vertical directions.

Precision Microdrives Z-axis LRA Linear Vibrator Motor

A magnetic field is generated by the voice coil which interacts with the magnet mass, which are suspended on a spring. As the magnetic field varies with the applied drive signal, the magnet and mass are moved up and down as they interact with the spring.

Resonant Frequency of Operation

Linear Vibrator LRA Resonant Frequency Bode Plot

Again, those readers familiar with vibration, RF, or audio engineering, will quickly spot that attaching a mass to a spring causes a resonance effect. The combination of spring stiffness, mass and magnet / coil size will cause the linear vibrator to have a natural resonant frequency.

This natural resonant frequency is where the LRA is most efficient in its operation, as can be seen by the output amplitude vs frequency on the bode plot above for our C10-100 Linear Resonant Actuator.

Extended Lifetime for Linear Vibrators

Unlike most vibration motors which have a electromechanical commutation, LRA vibration motors are effectively brushless as they use a voice-coil to drive the mass. This means that the only moving parts that are prone to failure are the springs. These springs are modelled with finite element analysis (FEA) and are operated within their non-fatigue zone.